A communication session frequently includes providing a caller with interactive features. For example, in a call center environment, a caller may be able to select certain options using an interactive voice response (IVR) system such as by speaking or pressing buttons. Some systems implement the interactive features using voice extensible markup language (VoiceXML). VoiceXML interpreters typically accept input from a caller in either dual tone multi-frequency (DTMF) or single input (either voice or text) form.